Authigenic molybdenum formation in marine sediments: a link to pore water sulfide in the Santa Barbara Basin

Zheng, Yan; Anderson, Robert F.; Geen, Alexander van; Kuwabara, James S.

doi:10.1016/s0016-7037(00)00495-6

Cited by 440 publications

(258 citation statements)

References 44 publications

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“…The nonzero values at depth are observed in profiles obtained by both sectioning/centrifugation and gel probe equilibration. Although we cannot be certain that concentrations do not decrease further below our maximum sampled depth, the observed values are similar to those that have been found in other locations (Shaw et al, 1990;Klinkhammer and Palmer, 1991;Colodner et al, 1993;Zheng et al, 2000Zheng et al, , 2002aMcManus et al, 2005;Morford et al, 2005).…”

Section: Measurements Of Excess 234supporting

confidence: 81%

“…Barnes and Cochran, 1993;Crusius et al, 1996;Zheng et al, 2000Zheng et al, , 2002aMcManus et al, 2005). Therefore, in order to set the stage for our discussion of RSM diagenesis, it is necessary to first discuss organic matter oxidation and redox horizons at the Hingham Bay site.…”

Section: Resultsmentioning

confidence: 99%

“…Zheng et al (2000) proposed that ~0.1 µM sulfide is the minimum concentration required to begin Mo-Fe-S precipitation, while ~100 µM sulfide is required for Mo precipitation without Fe. Therefore Mo reached its minimum concentration in…”

Section: Rsm: Diagenesismentioning

confidence: 99%

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Insights on geochemical cycling of U, Re and Mo from seasonal sampling in Boston Harbor, Massachusetts, USA

Morford

Martin

Kalnejais

et al. 2007

Geochimica et Cosmochimica Acta

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3Benthic chamber experiments including the nonreactive solute tracer, Br -, indicated that sediment irrigation was very important to solute exchange at the study site.The enhancement of sediment-seawater exchange due to irrigation was determined for the nonreactive tracer (Br -), TCO 2 , NH 4 + , U and Mo. The comparisons between these solutes showed that reactions within and around the burrows were very important for modulating the Mo flux, but less important for U. The effect of these reactions on Mo exchange was highly variable, enhancing Mo (and, to a lesser extent, U) uptake at times of relatively modest irrigation, but inhibiting exchange when irrigation rates were faster.These results reinforce the observation that Mo can be released to and removed from pore waters via sedimentary reactions.The removal rate of U and Mo from seawater by sedimentary reactions was found to agree with the rate of accumulation of authigenic U and Mo in the solid phase. The fluxes of U and Mo determined by in situ benthic flux chamber measurements were the largest that have been measured to date. These results confirm that removal of redoxsensitive metals from continental margin sediments underlying oxic bottom water is important, and suggest that continental margin sediments play a key role in the marine budgets of these metals.4

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Section: Measurements Of Excess 234supporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

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Insights on geochemical cycling of U, Re and Mo from seasonal sampling in Boston Harbor, Massachusetts, USA

Morford

Martin

Kalnejais

et al. 2007

Geochimica et Cosmochimica Acta

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“…High rates of primary productivity promote high export rates of agglomerated (brown and black) organic matter and high rates of sulfate-reduction and redoxsensitive trace metals are removed from bottom water to surface sediments in the form of metallic sulfurs (Valdés et al, 2004), as observed in other hypoxic environments (e.g. Santa Barbara Basin; Zheng et al, 2000). On the other hand, periods of lower primary productivity, organic matter deposition, and sulfate reduction rates are recorded as dispersed and yellowish organic matter (Valdés et al, 2004).…”

Section: Study Areamentioning

confidence: 98%

Oxygenation variability in Mejillones Bay, off northern Chile, during the last two centuries

Díaz-Ochoa

Pantoja²,

Lange

et al. 2011

Biogeosciences

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Abstract. The Peru Chile Current ecosystem is characterized by high biological productivity and important fisheries. Although this system is likely to be severely affected by climate change, its response to current global warming is still uncertain. In this paper, we analyze 10-166 year-old sediments in two cores collected from Mejillones Bay, an anoxic sedimentary setting favorable for the preservation of proxies. Based on a 166-year chronology, we used proxies of bottom-water oxygenation (Mo, V, S, and the (lycopane+n-C 35 )/n-C 31 ratio) and surface water productivity (biogenic opal, counts of diatom valves, biogenic Ba, organic carbon, and chlorins) to reconstruct environmental variations in Mejillones Bay. During the last two centuries, a shift took place in the coastal marine ecosystem of Bahia Mejillones at decadal scales. This shift was characterized by intense ENSO-like activity, largescale fluctuations in biological export productivity and bottom water oxygenation, and increased eolian activity (inferred from Ti/Al and Zr/Al). This short-term variability was accompanied by a gradual increase of sulfidic conditions that has intensified since the early 1960s.

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“…Different threshold levels of oxidant consumption trigger a series of reactions that lead to precipitation of U in the sediment (Zheng et al 2000). Authigenic U precipitation typically starts at the redox potential of Fe-oxide reduction (Zheng et al 2002).…”

Section: +mentioning

confidence: 99%

Behaviour of REEs in a tropical estuary and adjacent continental shelf of southwest coast of India: Evidence from anomalies

2012

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The distribution and accumulation of the rare earth elements (REE) in the sediments of the Cochin Estuary and adjacent continental shelf were investigated. The rare earth elements like La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the heavy metals like Mg, V, Cr, Mn, Fe, Cu, Zn, U, Th were analysed by using standard analytical methods. The Post-Archean Australian Shale composition was used to normalise the rare earth elements. It was found that the sediments were more enriched with the lighter rare earth elements than the heavier ones. The positive correlation between the concentrations of REE, Fe and Mn could explain the precipitation of oxyhydroxides in the study area. The factor analysis and correlation analysis suggest common sources of origin for the REEs. From the Ce-anomalies calculated, it was found that an oxic environment predominates in all stations except the station No. 2. The Eu-anomaly gave an idea that the origin of REEs may be from the feldspar. The parameters like total organic carbon, U/Th ratio, authigenic U, Cu/Zn, V/Cr ratios revealed the oxic environment and thus the depositional behaviour of REEs in the region.

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Authigenic molybdenum formation in marine sediments: a link to pore water sulfide in the Santa Barbara Basin

Cited by 440 publications

References 44 publications

Insights on geochemical cycling of U, Re and Mo from seasonal sampling in Boston Harbor, Massachusetts, USA

Insights on geochemical cycling of U, Re and Mo from seasonal sampling in Boston Harbor, Massachusetts, USA

Oxygenation variability in Mejillones Bay, off northern Chile, during the last two centuries

Behaviour of REEs in a tropical estuary and adjacent continental shelf of southwest coast of India: Evidence from anomalies

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